With the recent popularization of computers, ink jet printers have been widely used for making prints on paper, films, cloth and so on, not only in offices but also in homes.
The ink jet recording processes include a system in which ink droplets are ejected by the application of pressure with piezoelectric elements, a system in which bubbles are generated in ink by heat, thereby ejecting ink droplets, a system using a ultrasonic wave and a system in which ink droplets are sucked and ejected by electrostatic force. As inks for ink jet recording used in these systems, aqueous inks, oil-based inks and solid (melt type) inks are used. Of these inks, the aqueous inks have prevailed from the viewpoints of easy production, convenience in handling, odors and safety.
Coloring materials used in these inks for inkjet recording have been required to have excellent solubility in solvents, the possibility of high-density recording, good hues, excellent resistance against light, heat, air, water and chemicals, good fixing properties and the difficulty of blotting to image-receiving materials, excellent keeping quality as the inks, no toxicity, high purity and furthermore availability at low cost. However, it is extremely difficult to seek a coloring material satisfying these requirements at high levels. In particular, a coloring material having a good magenta hue and excellent in light fastness has been strongly desired.
Various dyes and pigments have been already proposed as those for ink jet, and practically used. However, no coloring material satisfying all of these requirements has been discovered yet under the present circumstances. It is difficult to allow both the hue and the fastness required for the inks for ink jet recording to be compatible with each other, by using the dyes and pigments that have hitherto been well known (such as those having Color Index (C.I.) Number). As dyes improving fastness, there have been proposed azo dyes derived from aromatic amines and 5-membered heterocyclic amines described in JP-A-55-161856 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”). However, these dyes have unfavorable hues in yellow and cyan regions, so that they have the problem of deteriorating color reproduction. JP-A-61-36362 and JP-A-2-212566 disclose inks for ink jet recording intending to allow hues and light fastness to be compatible. However, dyes used therein are insufficient in solubility in water, when used as water-soluble inks. Further, when the dyes described therein are used as water-soluble ink-jet ink, a problem is encountered also with regard to wet heat fastness. As means for solving these problems, there have been proposed compounds and ink compositions described in JP-T-11-504958 (the term “JP-T” as used herein means a published Japanese translation of a PCT patent application). Further, in order to improve hues and light fastness, inks for ink jet recording using pyrazolylanilineazo are described in Japanese Patent Application No. 2000-80733. However, in these inks for ink jet recording, it has become clear that deterioration of images occurs in some cases, when the inks are placed under severe conditions such as long-term storage at high temperatures, or when a gas such as a nitrogen oxide or ozone coexists therewith. In order to improve these disadvantages, the dye species has been studied. However, in gray or a secondary color such as blue, the effect of fastness is not sufficiently observed only when one kind of dye is changed, because of off-balanced hues. Further, the fastness becomes worse in some cases by an interaction due to mixing of two kinds of dyes. Accordingly, an ink set which can significantly improve the fastness, a cartridge, a printer using them, and highly fast printed matter have been desired.